[EyeB]

you could just buy a few sd cards :S

But harddrives are powered through the usb port, doubt phones can output that much to run them or you are stuck with one that plugs into wall, in this case a netbook would work just as well.

I've kind of managed to set up a network folder on my TP2 and using wifi share (then turn off data) I turned my phone into a wireless network and was able to share files with the things connected to it. Again bluetooth would save more battery doing this and you would need a netbook/laptop or a wireless HDD but this all don't have great battery life.